The present invention relates generally to substrate cleaning and drying and, more particularly, to systems, apparatuses, and methods for improving semiconductor substrate cleaning and/or drying by reducing contamination of substrate surfaces.
The fabrication of semiconductor devices involves numerous processing operations. These operations include, for example, dopant implants, gate oxide generation, inter-metal oxide depositions, metallization depositions, photolithography patterning, etching operations, chemical mechanical polishing (CMP), etc. As these operations generate particles and residues, wafer surfaces need to be cleaned so as to remove particulate contaminants adhered to the surfaces of the wafer.
Particulate contaminants generally consist of tiny bits of distinctly defined material having an affinity to adhere to the surfaces of the wafer. Examples of particulate contaminants can include organic and inorganic residues, such as silicon dust, silica, slurry residue, polymeric residue, metal flakes, atmospheric dust, plastic particles, and silicate particles, among others. Particulate contaminants should be removed from wafer surfaces as the existence of such contaminants can have detrimental effects on the performance of integrated circuit devices.
Cleaning the wafer front sides (i.e., the active side or top surface) has traditionally been given a higher priority in typical wafer cleaning systems and processes because deleterious defects may be caused in the processing of the wafers. However, as wafer sizes have increased and/or feature sizes have decreased, certain shortcomings have been associated with the failure to adequately and properly clean and process wafer backsides (i.e., non-active side).
One drawback of having contaminant particulates on wafer backside is particulate contaminant migration from the wafer backside to the wafer front side. For example, the migration may occur during a wet processing step and/or as the wafer is being moved or otherwise handled between the processing or metrology tools. Furthermore, the backside contaminants can undesirably migrate from one process tools or steps thus contaminating subsequent processes.
To eliminate such drawbacks, in certain substrate processing operations, first, the wafer backside is brush scrubbed using a roller type cleaning assembly followed by conditioning of the wafer front side. In the roller type cleaning assembly, a rotating brush is brought into contract with the wafer backside as fluid is supplied onto the cleaning interface. One of such exemplary fluids is SC1 defined as a mixture of ammonium hydroxide and hydrogen peroxide. When performing the brush scrubbing, however, undesirably, the cleaning fluid SC1 can in some cases be sprayed onto the wafer front side.
At this point, the wafer front side is conditioned in a cleaning module using a conditioning fluid such as a solution of hydrofluoric acid (HF) and DIW, which is not compatible with the SC1 brush scrubbing fluid. As a consequence of wafer front side cross contamination and incompatibility of SC1 and the HF solution, the quality of the cleaning operation may be reduced.
Aside from contaminating the wafer front side, cleaning wafer front side and backside using diverse and incompatible chemistries necessitates implementing an associate fluid handling arrangement and waste treatment unit for each of the implemented chemistries. By way of example, separate drainages and exhausts should be used to eliminate each of the chemistries from the cleaning chamber. As a direct result, not only the footprint of the wafer processing system is unnecessarily increased but also the system chemical handling arrangements can become very complicated.
In view of the foregoing, there is a need for a system, apparatus, and method for preparing substrates capable of implementing simplified fluid handling arrangements through improving substrate throughput by minimizing cross contamination resulting from using incompatible chemistries.